1. Field of the Invention
The present invention relates to a storage device (also referred to as a disk array device), and more particularly to failover technology of data path of an internal network of a storage controller.
2. Description of the Related Art
A storage device is typically provided with a storage controller (also referred to simply as a controller) and a random-accessible nonvolatile medium. The medium is, for example, a disk array including a large number of hard disk drives (HDD). The storage controller has a front-end interface (abbreviated as FEI/F) for connecting a host device (host system and the like), a back-end interface (abbreviated as BEI/F) for connecting a disk array, and a cache memory (abbreviated as CM) that temporarily stores data that the host device will write into the disk array and read therefrom. In addition, the storage controller includes a processor for controlling data transfer between the host device and cache memory and between the disk array and cache memory.
In a storage device requiring high reliability, a network in which the processor, FEI/F, BEI/F, and CM located in the storage controller are connected to each other is configured to enable failover when a data path failure occurs. Furthermore, in a storage device requiring high performance, a plurality of processors are connected to an internal network (abbreviated as CN) of a storage controller to control data transfer.
Well-known technology relating to a storage system equipped with an internal network (CN) enabling the failover when a data path failure occurs is described in Japanese Patent Application Published No. 2008-84066.
Furthermore, PCI Express (abbreviated as PCIe) is known as a standardized specification (base specification) relating to a network connecting the processor and FEI/F or BEI/F or the like. A “Multi-Root I/O Virtualization and Sharing Specification” (referred to hereinbelow as MR-IOV) for sharing an I/O device among a plurality of processors has also been standardized. Because, the MR-IOV is a standard, components such as switches that conform to the MR-IOV appear to be commoditized.
In other words, where an internal network (CN) of a storage controller is configured using the MR-IOV, which is a standard, the cost of the storage controller can be expected to be reduced.
“Single-Root I/O Virtualization and Sharing Specification” (referred to hereinbelow as SR-IOV) is also well known. In the SR-IOV, a plurality of SIs (System Image) can be accessed from one root port (abbreviated hereinbelow as RP) to a plurality of endpoint devices (abbreviated hereinbelow as EPDs). In the MR-IOV, a tree-like topology in which endpoints are viewed from one RP is called “virtual hierarchy” (referred to hereinbelow as VH). In the MR-IOV, a plurality of VHs are configured within the network, and one or more SIs can access a plurality of EPDs from one RP in each VH.